1. Field of the Invention
The present invention relates to an engine intake control device for adjusting air intake volume of an engine by driving an electric motor to open and close a throttle valve.
2. Description of the Related Art
An engine intake control device in which an electric motor is used to open and close a throttle valve for adjusting air intake volume of an engine has been put into practice.
Further, in recent years, a variable intake device that switches intake passages by utilizing intake pulsation and intake inertia to increase air intake volume over a wide range of engine revolutions for improving engine performance, and an air flow control valve device which controls an air flow introduced into a cylinder of an engine in accordance with operating conditions, and generates a swirl flow or a tumble flow to improve mixing condition of the fuel and air and combustion condition for improving engine performance and the exhaust gas have been adopted in many occasions.
As a driving source of these devices, a diaphragm type negative pressure actuator is often used. One or more solenoid valves are attached around the engine for switching between application of the negative pressure in the surge tank to the negative pressure actuator and interruption of applying the negative pressure. Hose piping for connection to the negative pressure passage, and wiring for electrical connection are provided for each of the solenoid valves (for example, see 2002–4 MAZDA ATENZA “maintenance manual” and 2003–9 MAZDA AXELA “introduction of new model cars”).
In the engine intake control device, brackets or screws are required for attachment of the respective solenoid valves. Assembling operations for providing the hose piping for connection to the negative pressure passage, and wiring for electrical connection are laborious. The cost of components, and the production cost are high.
Since considerable space is required for installing the solenoid valves, hose piping, and electrical wiring, it is difficult to downsize the engine intake control device. Further, the weight of these components is heavy.